It's a musical, played by Barbie(s)/Christie, Ken/Steven, a Barbie Britney Spears doll (all Mattel "Barbie-dolls"), all set up by Holly Dodd.

Holly's photos of Holly's Barbies (and Kens) for Holly's purposes
(a musical—you figure out which one)
Holly explains that they're now action figures, because you're not supposed to take their clothes off.